The present invention relates to ink jet compositions, generally, and in particular to jet ink compositions that are especially useful for marking on food items, especially candies, particularly chocolate.
Presently, most marking of information on food items, such as chocolate, is done by use of direct contact printing. Such a technique presents its own difficulty. Good print quality using direct contact printing is difficult to achieve when printing on nonuniform, irregular surfaces, as are presented when one attempts to print on chocolate. Damage, such as breakage, also is likely to occur, due to the irregular pressure applied to the chocolate. Inks used for food product contact printing, employing dyes, include those discussed in Japanese published applications JP 6073321; JP 3083559; and JP 1031878; U.S. Pat. Nos. 4,693,751 and 4,720,378; and Canadian patent 1,251,307.
Further, it is often useful to place variable information on food items, such as chocolate. A quick, easy manner of placing such information on such food items is presently desired. Also, desirable for brand recognition, is the ability to make images on the food item, as by ink printing a corporate logo or the like.
Ink jet printing would offer the advantage of increased speed of marking food products and the opportunity to put variable information on food items, such as chocolate.
Ink jet printing is a well-known technique by which printing is accomplished without contact between the printing device and the substrate on which the printed, characters are deposited. Ink jet printing systems are generally of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At this break-up point, the droplets are charged in accordance with digital data signals. These drops are then passed through an electrostatic field which adjusts the trajectory of each droplet. The droplets are either directed back to a gutter for recirculation or to a specific location on the substrate to create the desired character matrix.
In drop-on-demand systems, a droplet is expelled under pressure from a valve directly to a position on the substrate in accordance with the digital data signals. A droplet is not formed or expelled unless it is to be jetted to the substrate. Since drop-on-demand systems require no ink recovery, charging, or deflection, the system is much simpler than the continuous stream system.
A problem associated with the direct marking of food items, such as chocolate, however, is that the information on the chocolate must be and remain readable under a variety of conditions and must be stable. Because packaged or boxed chocolate is often subjected to changing conditions during transport, the surface of the chocolate can develop condensation or sweat. The printed information on the surface of the chocolate must remain readable even under such temperature and humidity extremes and sudden changes therein. The appearance of the printed image must not bleed, disappear, fade, or transfer to any packaging media placed in contact therewith, under any of the conditions and environmental changes that it may encounter.
To attempt to address this need for noncontact printing on food, some have employed the use of dye based food grade jet inks. Such inks, however, if printed onto dark candies, and the like, such as chocolate, fail to show up at all, or are only marginally readable. The problem, however, has been that ink used in such a fashion must meet the aforementioned rigid requirements, but also must be capable of being printed by use of existing ink jet printing equipment. Further, the printed image must be of food grade quality, edible and compliant with all applicable regulatory requirements such as those set forth by the U.S. Food and Drug Administration in the Code of Federal Regulations (CFR). Accordingly, there remains a need for a high quality ink jet composition that can be used to print by ink jet printing onto the surfaces of candies, such as chocolate, that will fulfill the rigid requirements as discussed above and yet be suitable for such a food-contact use, and thus comply with the list of acceptable ingredients as provided by governmental authorities such as the U.S. FDA.
Such an ink must be capable of providing printed images with good rub resistance, while employing components that are suitable for food contact.
Surprisingly, there has been discovered a white ink having good opacity when printed on a dark substrate, such as chocolate, which ink is comprised of components that are all acceptable for use on food for human consumption.
The present invention thus provides an ink composition for use in jet printing on food items, especially candies, particularly chocolate, and a method of forming printed images on such food items by use of such composition.
The composition of the present invention comprises pigment, preferably titanium dioxide, a binder and a carrier, preferably water.
The composition is free of components that are undesirable in an ink that is used for food contact, such as methyl ethyl ketone or acetone.